This invention relates generally to monitors for detecting a malfunction or failure of a computer and more specifically to a self-testing computer monitor. As used herein "self-testing" refers to the ability of a monitor to detect and indicate the failure of the monitor itself.
Computers are, of course, utilized in a variety of applications including the control of industrial machinery utilized to manufacture many types of products. In such applications it is especially important to detect a computer malfunction or failure since the computer controlled machinery may respond in a potentially harmful manner. The purpose of a computer monitor is to rapidly detect a hardware or system malfunction, such as a computer power supply failure or computer component failure, so that the machinery controlled by the computer can be safely stopped.
The ability of a monitor to protect the controlled equipment may be defeated by a failure of the monitor itself. In monitors of the type which utilize one output state as indicative of correct computer operation and another state as an indication of a computer failure, it is possible that a component of the monitor might fail so as to prevent the monitor from sensing or reacting to a computer failure. This type of monitor failure may only be discovered after a computer failure occurs which defeats the purpose of the monitor. The general purpose of the present invention is to provide a computer monitor capable of continually testing itself for proper operation as well as detecting a computer malfunction.